Lossless data compression may be used for purposes of reducing the size of data stored in mass storage, such as data stored on a magnetic tape, for example. One type of lossless data compression is LZ77 compression, in which strings of characters that appear more than once in the uncompressed data are replaced with references (called “copy pointers”) to the repeating strings. As the copy pointer is in general smaller than the size of the string it replaces, the size of the data is reduced. Decompressing LZ77-encoded data involves replacing copy pointers in the decompressed data with copies of the appropriate strings.